docs: def within(bbox, lonlat_index):
      """
      :param bbox: a bounding box in lon, lat
      :param lonlat_index: an rtree index in lon, lat
      :returns: array of indices within the bounding box
      """
      lon1, lat1, lon2, lat2 = bbox
      set_ = set()
      for l1, l2 in normalize_lons(lon1, lon2):
          box = (l1, lat1, l2, lat2)
          set_ |= set(lonlat_index.intersection(box))
      return numpy.array(sorted(set_), numpy.uint32)